using System;
using System.Collections.Generic;
using System.ComponentModel;
using System.ComponentModel.DataAnnotations;
using System.Linq;
using System.Reflection;
using System.Resources;
using System.Text;
using System.Threading.Tasks;

/// <summary>
/// 枚举扩展
/// </summary>
public static class EnumExtension
{
    /// <summary>
    /// 获取枚举描述
    /// </summary>
    /// <param name="enumType">枚举类型</param>
    /// <returns></returns>
    public static string GetEnumDisplayName(this Enum enumType)
    {
        try
        {
            Type type = enumType.GetType();
            var field = type.GetField(Enum.GetName(type, enumType));
            var attr = field.GetCustomAttribute<DisplayAttribute>();
            var attr2 = field.GetCustomAttribute<DescriptionAttribute>();
            if (attr == null && attr2 == null)
            {
                return enumType.ToString();
            }
            else if (attr == null && attr2 != null)
            {
                if (string.IsNullOrWhiteSpace(attr2.Description))
                    return enumType.ToString();
                else
                    return attr2.Description;
            }
            else if (attr != null && attr2 != null)
            {
                if (!string.IsNullOrWhiteSpace(attr.Name))
                    return attr.Name;
                if (!string.IsNullOrWhiteSpace(attr2.Description))
                    return attr2.Description;
                return enumType.ToString();
            }
            else
            {
                if (string.IsNullOrWhiteSpace(attr.Name))
                    return enumType.ToString();
                else
                    return attr.Name;
            }
        }
        catch
        {
            return enumType.ToString();
        }

    }

    public static T GetEnumByDisplayName<T>(this string displayName) where T : struct
    {
        Type type = typeof(T);
        string[] names = Enum.GetNames(type);
        string[] array = names;
        foreach (string text in array)
        {
            DisplayAttribute customAttribute = type.GetField(text).GetCustomAttribute<DisplayAttribute>();
            DescriptionAttribute da = type.GetField(text).GetCustomAttribute<DescriptionAttribute>();

            T result;
            if (customAttribute == null && da == null)
            {
                if (text == displayName && Enum.TryParse(text, out result))
                {
                    return result;
                }
                continue;
            }
            string a;
            if (customAttribute != null)
            {
                if (customAttribute.ResourceType == null && string.IsNullOrEmpty(customAttribute.Name))
                {
                    a = text;
                }
                else if (customAttribute.ResourceType == null)
                {
                    a = (string.IsNullOrEmpty(customAttribute.Name) ? text : customAttribute.Name);
                }
                else
                {
                    ResourceManager resourceManager = new ResourceManager(customAttribute.ResourceType);
                    a = resourceManager.GetString(customAttribute.Name);
                }
            }
            else
            {
                if (da == null && string.IsNullOrEmpty(da.Description))
                {
                    a = text;
                }
                else
                {
                    a = (string.IsNullOrEmpty(da.Description) ? text : da.Description);
                }
            }

            if (a == displayName && System.Enum.TryParse(text, out result))
            {
                return result;
            }
        }
        throw new Exception($"{displayName}转换为枚举{typeof(T)}失败");
    }

}